Device and method for separating a material

Abstract

A method for separating a workpiece includes providing ultrashort laser pulses using an ultrashort pulse laser, and introducing material modifications into the workpiece along a separation line using the ultrashort laser pulses. The workpiece includes a transparent material. The method further includes separating the material of the workpiece along the separation line. The laser pulses form a laser beam that is incident onto the workpiece at a work angle. An optical aberration of the laser pulses during a transition into the material of the workpiece is reduced by an aberration correction device. The laser beam has a non-radially symmetric transverse intensity distribution, with the transverse intensity distribution appearing elongate in a direction of a first axis in comparison with a second axis perpendicular to the first axis.

1 . A method for separating a workpiece, the method comprising:
 providing ultrashort laser pulses using an ultrashort pulse laser,   introducing material modifications into the workpiece along a separation line using the ultrashort laser pulses, the workpiece comprising a transparent material, and   separating the material of the workpiece along the separation line,   wherein the laser pulses form a laser beam that is incident onto the workpiece at a work angle, and an optical aberration of the laser pulses during a transition into the material of the workpiece is reduced by an aberration correction device, and   wherein the laser beam has a non-radially symmetric transverse intensity distribution, with the transverse intensity distribution appearing elongate in a direction of a first axis in comparison with a second axis perpendicular to the first axis.   
     
     
         2 . The method according to  claim 1 , wherein the material modifications penetrate two sides of the workpiece that are located in intersecting planes, and separating the material of the workpiece produces a shaped edge. 
     
     
         3 . The method according to  claim 2 , wherein the shaped edge comprises a chamber or a bevel, a length of a hypotenuse of the chamfer or the bevel is between 50 μm and 2 mm. 
     
     
         4 . The method according to  claim 1 , wherein the material modifications are Type III modifications that are associated with a formation of cracks in the material of the workpiece. 
     
     
         5 . The method according to  claim 1 , wherein separating the material of the workpiece comprises mechanical separation, and/or etching, and/or application of heat, and/or self-separation. 
     
     
         6 . The method according to  claim 1 , wherein the laser beam is a non-diffractive laser beam. 
     
     
         7 . The method according to  claim 6 , wherein in a projection of the non-radially symmetric transverse intensity distribution onto the workpiece appears to have a same size along the first axis and the along the second axis as a result of the work angle, and/or the projection of the non-radially symmetric transverse intensity distribution onto the workpiece is elongated in the feed direction. 
     
     
         8 . The method according to  claim 6 , wherein a projection of the non-radially symmetric transverse intensity distribution onto the workpiece is elongated in a feed direction. 
     
     
         9 . The method according to  claim 1 , wherein a pulse energy of the laser pulses is between 10 μJ and 50 mJ, and/or a mean laser power is between 1 W and 1 kW, and/or a wavelength of the laser pulses is between 300 nm and 1500 nm, and/or the laser beam is polarized parallel to a plane of incidence. 
     
     
         10 . The method according to  claim 1 , wherein the laser pulses are individual laser pulses or part of a laser burst, the laser burst comprising 2 to 20 laser pulses, and the laser pulses of the laser burst have a temporal spacing of 10 ns to 40 ns. 
     
     
         11 . A device for separating a workpiece comprising a transparent material, the device comprising:
 an ultrashort pulse laser configured to provide ultrashort laser pulses,   a processing optical unit configured to introduce the laser pulses into the material of the workpiece,   a feed device configured to move a laser beam formed by the laser pulses and the workpiece relative to one another with a feed along a separation line, and to orient an optical axis of the processing optical unit at a work angle relative to a surface of the workpiece, and   an aberration correction device configured to reduce an aberration of the laser pulses upon entrance into the material of the workpiece, wherein   the laser beam is incident onto the workpiece at a work angle, and the laser beam has a non-radially symmetric transverse intensity distribution,   with the transverse intensity distribution appearing elongate in a direction of a first axis in comparison with a second axis perpendicular to the first axis.   
     
     
         12 . The device according to  claim 11 , further comprising a beam shaping optical unit configured to shape a non-diffractive laser beam from the laser beam. 
     
     
         13 . The device according to  claim 11 , wherein the aberration correction device has a first surface and a second surface, wherein the first surface is disposed upstream of the second surface in a beam propagation direction, the first surface is cylindrically arched and the second surface is cylindrically arched or planar, and the second surface is a last surface in a beam path of the laser beam before the laser pulses are introduced into the material of the workpiece, and/or the aberration correction device is formed in one piece in a form of a cylindrical wedge, and/or a distance of the second surface from a material surface is less than 1 mm, and/or the aberration correction device is mounted interchangeably in an insertion cassette. 
     
     
         14 . The device according to  claim 11 , wherein the processing optical unit comprises the aberration correction device and/or the processing optical unit comprises a telescope system configured to introduce the laser beam with a reduced and/or increased size into the material of the workpiece. 
     
     
         15 . The device according to  claim 11 , wherein the feed device comprises an axis device and a workpiece holder that are configured to move the processing optical unit and the workpiece relative to one another along three spatial axes in translational fashion and about at least two spatial axes in rotational fashion, and/or the work angle of the processing optical unit is between 0 and 60°, and/or component laser rays of the laser beam are incident on the workpiece at an angle of incidence of no more than 80° with respect to a surface normal of the workpiece, and/or the axis device is adjusted for aligning a long axis of the non-radially symmetric transverse intensity distribution along the feed direction, and/or the workpiece holder has a surface that does not reflect and/or scatter the laser beam. 
     
     
         16 . The device according to  claim 11 , further comprising a polarization optical unit that comprises a polarizer and a waveplate, wherein the polarization optical unit is configured to adjust a polarization of the laser beam relative to a plane of incidence of the laser beam. 
     
     
         17 . The device according to  claim 16 , wherein the polarization optical unit is configured to set the polarization of the laser beam parallel to the plane of incidence. 
     
     
         18 . The device according to  claim 11 , further comprising a beam guiding device configured to guide the laser beam to the material, wherein the beam guiding device comprises a mirror system and/or an optical fibre. 
     
     
         19 . The device according to  claim 11 , further comprising control electronics configured to trigger a laser pulse emission of the ultrashort pulse laser based on relative positions of laser beam and the material.